Storage of ripe apricot (Prunus armeniaca) fruit at low temperatures results in the loss of volatile aroma compounds. Here, we analyzed volatile compounds in fruit from the apricot cultivars ‘Chuanzhihong’ and ‘Mituoluo’ during ripening and identified esters as key contributors to fruit aroma. The cultivars accumulated different profiles of volatiles during ripening. Transcriptome analysis identified more than 20,000 genes that were differentially expressed during fruit development and a cluster of genes that were enriched in KEGG pathways associated with fatty acid–derived ester biosynthesis. The key ester biosynthetic genes LOX and AAT were upregulated during fruit ripening but suppressed at low temperatures. Volatile emissions dropped below 10 °C and partially recovered at 25 °C, but LOX and AAT enzymatic activities failed to recover, leading to diminished aroma. Storage at 0–5 °C caused a strong and largely irreversible suppression of ester accumulation, even after rewarming.

Environmental stresses, especially high temperatures, severely limit the growth and development of many horticultural plants. As a woody ornamental flower with rich flower colors and flower types, rose (R. chinensis) leaves wilt and shriveled petals at high temperatures, which severely affects its growth and ornamental value. The defense mechanism of rose plants against high-temperature stress has not been fully elucidated. In the present study, the transcriptomes of rose petals at normal (25 °C) and high (35 °C) temperature were compared. A total of 2519 differentially expressed genes (DEGs) were identified, including 1491 upregulated DEGs and 1028 downregulated DEGs. The plant hormone signal transduction pathway, especially the abscisic acid (ABA) signaling pathway, was the most enriched signaling pathway for DEGs in rose at high temperature. Heat shock factors (Hsfs), especially class A Hsfs, have been confirmed to be involved in thermotolerance mechanisms. Among the DEGs, eight genes were annotated as Hsfs, including 5 upregulated Hsfs at high temperature. RcHsfA6 is rapidly induced by high temperatures and is a candidate regulatory factor in the plant ABA signaling pathway. Therefore, we focused on RcHsfA6. RcHsfA6 encodes a protein containing 308 amino acids and contains typical Hsf domains, such as the DNA-binding domain (DBD), the N-terminal oligomerization domain (OD), the nuclear localization signal (NLS) and AHA motifs at the C-terminal activator domain (CTAD). The heterologous overexpression of RcHsfA6 in Arabidopsis increased the thermotolerance of Arabidopsis seeds. In addition, RcHsfA6 overexpression increased the ABA content and the expression of ABA biosynthetic gene AtABI5 and signal transduction gene AtPYL12, thereby inhibiting the germination of Arabidopsis seeds under exogenous ABA conditions. Taken together, our results suggest that RcHsfA6 is involved in the high-temperature response of rose and its heterologous overexpression in Arabidopsis increased the thermotolerance of Arabidopsis at high temperatures via the ABA signaling pathway.

Rose is a famous ornamental flower worldwide, and its flower color is an important ornamental trait. The formation of yellow petals is primarily determined by carotenoids, yet its regulatory mechanism is largely unknown. Here, the main carotenoid components in yellow petals were β-carotene and violaxanthin. The enzyme-encoding genes playing a crucial role in the carotenoid biosynthesis pathway were RhLYCB, RhZEP, and RhVDE. Transcription factors RhMYB3, RhMYB305, RhMYB30, and RhERF23 were identified as key regulatory genes based on transcriptomics and metabolomics. Transcript levels of these genes were closely associated with petal coloration during flower development and in an F1 population. Overexpression of RhMYB3, RhMYB305, RhMYB30, and RhERF23 significantly promoted carotenoid accumulation, as well as the expression of structural genes, in both rose petals and tobacco leaves. Further validation through molecular interaction (Yeast single hybrid and EMSA) confirmed that these genes bound to the promoter of RhLCYB and RhCRTISO, thereby activating their expressions and contributing to the enhanced carotenoid content. Moreover, RhMYB305 interacting with RhMYB3, RhMYB30, and RhERF23 promotes carotenoid accumulation in tobacco leaves and rose petals. Collectively, we propose that RhMYB3, RhMYB305, RhMYB30, and RhERF23 play a pivotal role in enhancing carotenoid biosynthesis, which will facilitate the modulation of carotenoid accumulation in rose and quality breeding through molecular design.

Red walnuts have been widely studied because of their strong antioxidant activity and ornamental value. However, research on the mechanism of anthocyanin biosynthesis in walnuts remains in the initial stage. The regulatory mechanism of TT2-type R2R3-MYB transcription factors in anthocyanin biosynthesis in walnuts is also unclear. Therefore, this study used ‘D2-1’ and ‘Jinghong 1’ walnuts as plant materials. The testa of ‘Jinghong 1’ was red, and its anthocyanin content was significantly higher than that of ‘D2-1’, mainly composed of cyanidin-3-O-arabinoside, cyanidin-3-O-galactoside, and cyanidin-3-O-glucoside. Differentially expressed genes between ‘D2-1’ and ‘Jinghong 1’ testa were enriched in phenylpropanoid biosynthesis and flavonoid biosynthesis. Next, this study identified a TT2-type R2R3-MYB transcription factor JrMYB1L, which was involved in regulating the anthocyanin biosynthesis in the testa of ‘Jinghong 1’. The overexpression of JrMYB1L could promote anthocyanin accumulation in walnut leaves and activate the expression of JrCHS, JrCHI, JrF3H, JrDFR, JrANS, JrUFGT, JrLAR, and JrANR. In addition, yeast two-hybrid results proved that JrMYB1L, JrbHLH42, and JrWD40 proteins could interact with each other. The results of yeast one-hybrid and dual-luciferase assays indicated that JrMYB1L could activate the expression of JrCHS and JrUFGT by binding to their promoters. Based on the above results, this study proposed a possible regulatory mechanism. JrMYB1L activated the expression of JrCHS and JrUFGT in the form of JrMYB1L-JrbHLH42-JrWD40 complex, thereby promoting anthocyanin accumulation in the testa of ‘Jinghong 1’. In summary, this study lays a theoretical foundation for revealing the regulatory mechanism of anthocyanin biosynthesis in red walnut and contributes to the breeding of new varieties of red walnuts with more edible and ornamental value.

Gene editing is more challenging in octoploids due to the presence of multiple copies of each gene. However, the ability to edit genes in these plants would allow editing in commercial varieties. Here, we delivered sequences targeting FaMYB9 into octoploid strawberry "Honeoye" and identified several gene-edited lines. Among them, the heterozygous gene-edited line FaMYB9CR-15 had curved and wrinkled leaves at 3 months, whereas leaves of 3-month-old wild-type (WT) strawberry seedlings were elliptical with a smooth surface. At that stage, FaMYB9CR-15 leaves also had large patches of wax. We identified 11,402 differentially expressed genes, divided into four clusters, between WT and FaMYB9CR-15 seedlings at 3 months. Notably, cluster 4 genes-related to nonhomologous end joining, microhomology-mediated end joining repairs, homologous recombination, nucleotide excision repair, and mismatch repair-were more highly expressed in the gene-edited line than in the WT. Surprisingly, by 6 months of age, FaMYB9CR-15 leaves had become smooth with small patches of wax, and expression levels of cluster 4 genes were significantly lower than at 3 months. Over the same period, the percentage of FaMYB9 loci harboring the mutant allele decreased from 70.2% to 43.7%. These findings lead us to conclude that there could be reversion of mutated sequences in octoploid strawberry, emphasizing the challenges of gene editing high-ploidy materials.

In plants, the R2R3-MYB transcription factors are one of the largest MYB gene families. These MYB transcription factors are very important for regulating plant growth and development. RcMYB114, RcbHLH, and RcWD40 promote anthocyanin accumulation by forming the MBW (MYB-bHLH-WD40) complex and determine the rose flower’s color. RcMYB114 genomic sequences differ between the red petal and white varieties. Two non-synonymous substitutions were found in the open reading frame. It leads to a change in amino acids. Here, the anthocyanin content showed that there was no anthocyanin in white petals, while the anthocyanin content in red petals increased firstly at stage 2, decreased slightly at stage 4, and then increased again at stage 5. The spatiotemporal expression pattern analysis showed that RcMYB114 was not expressed in all petals and tissues of white petals at different flower development stages. In red petal varieties, RcMYB114 was highly expressed in petals, followed by styles, and not expressed in stems, young leaves, and stage 1 of flower development. However, RcMYB114 has the highest expression level at the blooming stage. The RcMYB114 sequence contains 9 SNPs in the coding region, 7 of which were synonymous substitutions that had no effect on the translation product and 2 of which were non-synonymous substitutions that resulted in amino acid alteration at positions 116 and 195, respectively. The RcMYB114 gene in red rose was named RcMYB114a, and in white rose was RcMYB114b. RcMYB114c was mutated into leucine via artificial mutation; it was valine at position 116 of RcMYB114a, and Glycine mutated into Arginine at position 195 of RcMYB114a was RcMYB114d. RcMYB114b was the double mutation at positions 116 and 195 of RcMYB114a. The results of yeast two-hybrid experiments showed that RcMYB114a and its missense mutations RcMYB114b, RcMYB114c, and RcMYB114d could both interact with RcbHLH and RcWD40 to form the MYB-bHLH-WD40 complex. A transient transformation experiment in tobacco confirmed that RcMYB114a and its missense mutations RcMYB114b, RcMYB114c, and RcMYB114d could significantly promote the high expression of related structural genes in tobacco, together with the RcbHLH gene, which led to the accumulation of anthocyanins and produced the red color of the leaves. The RcMYB114a gene and its missense mutations RcMYB114b, RcMYB114c, and RcMYB114d interacted with the RcbHLH gene and significantly regulated the accumulation of anthocyanins. The two non-synonymous mutations of RcMYB114 do not affect the function of the gene itself, but the content of the anthocyanins accumulated was different. This study should provide clues and references for further research on the molecular mechanism underlying the determination of rose petal color.

Heat shock transcription factors (Hsfs) play an important role in response to high temperatures by binding to the promoter of the heat shock protein gene to promote its expression. As an important ornamental plant, the rose often encounters heat stress during the flowering process. However, there are few studies on the Hsf family in roses (Rosa. chinensis). In the current study, 19 Hsf genes were identified from R. chinensis and grouped into three main subfamilies (A, B, and C) according to their structural characteristics and phylogenetic analysis. The expression patterns of RcHsf genes were detected in different tissues by quantitative real-time PCR. The RcHsf genes exhibited distinct expression patterns at high temperatures, with RcHsf17 having the highest expression level. RcHsf17 was localized in the nucleus and had transcriptional activity. The overexpression of RcHsf17 increased thermotolerance in Arabidopsis, suggesting the potential role of RcHsf17 in the regulation of the high-temperature response. In addition, RcHsf17 overexpressed in Arabidopsis could enhance the response of transgenic Arabidopsis to methyl jasmonate. Collectively, this study identified and screened RcHsfs in response to high temperatures in roses, providing new insights into the functional divergence of RcHsfs and a basis for screening new varieties of rose.

Rambutan is a tropical tree and its fruit has several favorable characteristics. To understand how the color of the rambutan fruit peel develops, the transcriptome, flavonoid metabolome, and carotenoid metabolome data of two rambutan cultivars, ‘BY2’ and ‘BY7’, which show yellow and red peels at maturity, respectively, were comprehensively analyzed at three developmental stages. We identified 26 carotenoid components and 53 flavonoid components in these cultivars. Anthocyanins were the main component contributing to the red color of ‘BY7’ after reaching ripeness. The carotenoid content decreased sharply as the fruit matured. Hence, we speculated that flavonols were the main contributors to the yellow color of the ‘BY2’ peel. In total, 6805 differentially expressed genes were screened by transcriptome analysis; the majority of them were enriched in metabolic pathways and the biosynthesis of secondary metabolites. Weighted gene co-expression network analysis results revealed that in addition to MYB and bHLH, ERF, WRKY, MYB-related, and C3H were the main potential transcription factors regulating the color of the rambutan peel. In addition, we also identified 12 structural genes associated with flavonoid biosynthesis. The research findings shed light on the molecular mechanisms of color acquisition in rambutan fruit peels, laying the foundation for the quality control of rambutan and the cultivation of differently colored cultivars of rambutan.

Scent is the key character of the horticultural ornamental plant rose, and benzenoid–phenylpropanoid compounds are the main source of scent. However, the underlying biosynthesis mechanism of these benzenoid–phenylpropanoid scent metabolites during Rosa flowering is poorly understood. In this study, the volatile metabolome and transcriptome conjoint analysis was conducted on the six stages petals of the variety ‘Lanxing’ to investigate the synthesis of benzenoid–phenylpropanoid metabolites. A total of 25 benzenoid–phenylpropanoid volatile compounds were identified, of which eugenol possessed the highest content. Meanwhile, transcriptome analysis produced 87.9 million clean reads and 22,004 differentially expressed genes (DEGs). Group pairwise comparison of gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis found DEGs were enriched into phenylpropanoid compound synthesis related pathway. Weighted gene co-expression network analysis (WGCNA) found a MEgreenyellow gene module (650 DEGs) correlated with phenylpropanoid compounds. Based on the eugenol content variation and gene spatio-temporal expression, a key candidate gene RcEGS32 related to the synthesis of eugenol was identified. Co-expression network analysis found that five transcription factors, RcMYB1, RcBES1, RcERF2, RcbHLH1, and RcTUB, may act as regulators in the eugenol synthesis process by directly binding to RcEGS32 or forming a complex unit. This study provided key insights into the formation of the scent substance eugenol during flowering, offering a valuable volatile metabolome and transcriptome resource for the future target trait-related gene discovery of roses.

The increasing ground-level ozone (O3) pollution resulting from rapid global urbanization and industrialization has negative effects on many plants. Nonetheless, many gaps remain in our knowledge of how ornamental plants respond to O3. Rose (Rosa hybrida L.) is a commercially important ornamental plant worldwide. In this study, we exposed four rose cultivars ("Schloss Mannheim," "Iceberg," "Lüye," and "Spectra") to either unfiltered ambient air (NF), unfiltered ambient air plus 40 ppb O3 (NF40), or unfiltered ambient air plus 80 ppb O3 (NF80). Only the cultivar "Schloss Mannheim" showed significant O3-related effects, including foliar injury, reduced chlorophyll content, reduced net photosynthetic rate, reduced stomatal conductance, and reduced stomatal apertures. In "Schloss Mannheim," several transcription factor genes-HSF, WRKY, and MYB genes-were upregulated by O3 exposure, and their expression was correlated with that of NCED1, PP2Cs, PYR/PYL, and UGTs, which are related to ABA biosynthesis and signaling. These results suggest that HSF, WRKY, and MYB transcription factors and ABA are important components of the plant response to O3 stress, suggesting a possible strategy for cultivating O3-tolerant rose varieties.

以月季'月月红'(Rosa chinensis' Slater's Crimson China')和'2015-58-20'(Rosa sp.)为材料进行自交和异交,授粉花柱中花粉管荧光显微镜观察结果显示月季为典型的配子体自交不亲和植物.通过与已知蔷薇科自交不亲和S-RNase基因的序列进行比对,在'月月红'中克隆到RcS1-RNase和RcS2-RNase基因的cDNA和DNA全长序列,序列分析表明,RcS1-RNase和RcS2-RNase具有5个保守结构域(C1、C2、C3、RC4和C5)和1个高变区.系统进化分析发现,RcS-RNase与其他蔷薇科植物的S-RNase蛋白具有较高的同源性.组织特异性表达分析表明,RcS1-RNase和RcS2-RNase基因只在花柱中特异表达.

Rose (Rosa sp.) flowers have a rich diversity of colors resulting from the differential accumulation of anthocyanins, flavonols, and carotenoids. However, the genetic and molecular determinants of the red-petal trait in roses remains poorly understood. Here we report that a transposable element-like insertion (Rosa1) into RcMYB114, a R2R3-MYB transcription factor’s promoter region causes its transcription, resulting in red petals. In red-petal varieties, RcMYB114 is expressed specifically in flower organs, but is absent from non-red varieties. Sequencing, yeast two-hybrid, transient transformation, and promoter activity assays of RcMYB114 independently confirmed the role of Rosa1 in altering RcMYB114’s transcription and downstream effects on flower color. Genetic and molecular evidence confirmed that the Rosa1 transposable element-like insertion, which is a previously unknown DNA transposable element, is different from those in other plants and is a reliable molecular marker to screen red-petal roses.

以月季红色花品种'卡罗拉'(Rosa hybrida'Carola')为材料,从其花瓣cDNA中克隆到1个R2R3-MYB基因,命名为RhMYB113c.其开放阅读框为699 bp,编码233个氨基酸.蛋白多重序列比对分析发现RhMYB113c含有R2和R3结构域.系统进化树分析表明,RhMYB113c与花青素苷合成激活因子AtMYB114、AtMYB113、AtMYB75、AtMYB90亲缘关系最近.组织特异性表达检测发现,RhMYB113c主要在'卡罗拉'花瓣和花柱中表达,在白色花品种'白缎'所有组织中均不表达.不同花发育时期的基因表达显示,RhMYB113c在'卡罗拉'未着色花瓣中不表达,在盛花期花瓣中高表达,而在白色品种的每个时期均不表达.酵母双杂交和烟草瞬时表达试验证实RhMYB113c调控花青素苷的合成,从而影响月季红色花瓣着色.

Roses ( Rosa sp.) are an important ornamental crop worldwide. Their colorful flowers mainly reflect an accumulation of anthocyanins and carotenoids. Developing a reliable method to classify rose petal color and identifying relationships between pigment contents and color space values may offer better evaluation criteria for rose varieties. In this study, we classified 60 rose varieties into three groups based on their color parameters, corresponding to red varieties, white and yellow varieties, and pink and dark pink varieties. We measured the total pigment contents and identified the underlying anthocyanins and carotenoids using both UV spectrophotometry and ultraperformance convergence chromatography coupled to mass spectrometry. Flower petals of white roses contained the lowest pigment levels, while those of yellow roses contained only carotenoids (40.65–244.42 µg/g) and mainly in the form of β-carotene and violaxanthin. The petals of pink and dark pink roses only accumulated anthocyanins (91.72–1703.93 µg/g) and mainly as cyanidin 3,5-diglucoside and cyanidin 3- O -glucoside. The petals of red roses contained both large amounts of anthocyanins (1484.8–3806.22 µg/g) and small amounts of carotenoids (1.81–18.77 µg/g). We divided the 60 rose varieties tested here into five color groups based on optical spectrum and pigment content analyses. We also explored the relationships between anthocyanin contents, carotenoid contents, and flower color space values using principal component analysis, Pearson’s correlations, and non-linear models. In addition to providing a more accurate system of rose petal color classification, our results can be used to predict pigment contents based on color parameters.

花青素是使草莓(Fragaria×ananassa)果实着色的重要色素,FaMYB10是花青素合成调控的关键转录因子.为了明确FaMYB10等位基因的核苷酸多态性在烟草(Nicotiana benthamiana)花青素积累中的作用,本研究通过同源克隆的方法,从草莓果实中分离出FaMYB10的3个等位基因,从草莓红色品种'甜查理'中鉴别出等位基因 FaMYB10a(GenBank No.MW478285)和 FaMYB10b(GenBank No.MG456859),从白色品种'白雪公主'的果实中鉴定出等位基因FaMYB10c(GenBankNo.MG456860).序列分析表明,FaMYB10a和FaMYB10b的开放阅读框长702 bp,编码233个氨基酸,从起始密码子ATG开始在94 bp处存在1个核苷酸多态性位点,FaMYB10a为碱基A,FaMYB10b则为碱基C;FaMYB10c的开放阅读框长710 bp,从ATG开始在491 bp处有8个碱基插入,导致提前终止,编码179个氨基酸.FaMYB10c在开放阅读框中的碱基插入导致与其他2个等位基因在理化性质和蛋白结构上产生差异.利用瞬时转化技术将3个FaMYB10等位基因在烟草叶片中进行过表达,转FaMYB10a和FaMYB10b的叶片过表达区域出现花青素积累的现象,呈现红色表型;而转FaMYB10c 的叶片过表达区域没有出现花青素积累的现象.以上结果说明等位基因FaMYB10a和FaMYB10b核苷酸多态性不影响花青素积累,而等位基因FaMYB10c的核苷酸多态性导致功能改变,最终烟草叶片不能积累花青素.该研究为其他重要基因的功能研究提供借鉴,对于植物性状差异和演化研究提供参考依据.

Background Strawberry ( Fragaria × ananassa Duch.) is an important fruit crop worldwide. It was particularly sensitive to drought stress because of their fibrous and shallow root systems. Mutation of Arabidopsis thaliana ROOTY ( RTY ) results in increased endogenous auxin levels and roots and shoot growth, but the effects of this gene in strawberry remain unclear. Results Here, we heterologously expressed Arabidopsis rty in strawberry plants and examined the effects of rty expression on the hormonal and physiological properties of the plants. Heterologous expression of rty induced IAA accumulation and increased the production of adventitious roots as well as trichomes on the abaxial leaf surface of the transgenic plants. Furthermore, the transgenic strawberry plants had increased ABA accumulation and stomatal closure. The transgenic strawberry plants exhibited enhanced water use efficiency and a reduced water loss rate. Additionally, peroxidase and catalase activities were significantly higher in the transgenic plants than in the untransformed controls, and the transgenic plants were more drought tolerant than the wild-type plants. Our results uncover a transgenic approaches can be used to overcome the inherent trade-off between plant growth and drought tolerance by enhancing water use efficiency and reducing water loss rate under water shortage conditions. Conclusions In this study, the rty gene improves hormone-mediated drought tolerance in transgenic strawberry. We demonstrated that the heterologous expression of rty in strawberry improved drought tolerance by promoting auxin and ABA accumulation. These phytohormones together brought about various physiological changes that improved drought tolerance via increased root production, trichome density, and stomatal closure. This study provides the basis for future genetic modifications of strawberry to improve drought tolerance.

Octoploid strawberry (Fragaria x ananassa Duch.) is a model plant for research and one of the most important non-climacteric fruit crops throughout the world. The associations between regulatory networks and metabolite composition were explored for one of the most critical agricultural properties in octoploid strawberry, fruit colour. Differences in the levels of flavonoids are due to the differences in the expression of structural and regulatory genes involved in flavonoid biosynthesis. The molecular mechanisms underlying differences in fruit colour were compared between red and white octoploid strawberry varieties. FaMYB genes had combinatorial effects in determining the red colour of fruit through the regulation of flavonoid biosynthesis in response to the increase in endogenous ABA at the final stage of fruit development. Analysis of alleles of FaMYB10 and FaMYB1 in red and white strawberry varieties led to the discovery of a white-specific variant allele of FaMYB10, FaMYB10-2. Its coding sequence possessed an ACTTATAC insertion in the genomic region encoding the C-terminus of the protein. This insertion introduced a predicted premature termination codon, which suggested the loss of intact FaMYB10 protein playing a critical role in the loss of red colour in white octoploid strawberry.